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The Regulation of Innate Immune Responses to Endoparasites in Lepidopteran and Dipteran Larvae
B.A. Webb, S. Govind
Department of Entomology
Immune responses of insects to parasitic wasps are poorly understood but criticial to the efficacy of biological control in natural and agroecosystems. This project will describe the basic immune responses to allow better prediction of the results of biocontrol and possibly identify important genes from insects that could be useful for insect control.
2009 Project Description
This project has resulted in the following primary outputs.
1. Development of a H. virescens microarray chip for use in hybridizations to test for alterations in immune function. This chip has been tested and used to define the response to immune challenge with lipopolysaccharide and laminarin. We are currently defining the immune responses to challenge with parasitoid eggs and larvae and the impact of immunosuppression by the Campoletis sonorensis polydnavirus.
2. We have demonstrated that similar immune responses occur in H. virescens and Drosophila in microarrays and also that NF-kb signalling is affected by viral ankyrin genes in mammalian cells.
3. We have demonstrated that the unique effects of some viral ankyrin genes are related to a novel putative zinc binding domain on the viral ankyrins p-vank-1 and I2-ank3 and implicated the apoptotic signaling pathway in mediating the divergent effects observed in response to challenge with these polydnavirus ankyrin genes.
4. The venom gland of the parasitoid wasp L. heterotoma, has been characterized and novel canal-like features described which are linked to immunosuppressive function in the secreted proteins. A paper reporting these results is in the final stages of review.
The principal project outcomes/impacts are as follows:
1. A presentation of the microarray development and initial evaluation was presented at the Entomological Society of America.
2. The characterization of H. virescens signaling has opened new opportunities for collaboration and led to a BARD proposal submission to evaluate effects of viruses on immune signaling. The demonstration that polydnaviral ankyrins interact with mammalian IKB signaling pathways has led to a new collaboration with Dr. Tony Sinai that is directly derived from this project. A proposal submission and paper on this work is anticipated in 2009.
3. The finding that polydnavirus ankyrins block cellular apoptotic pathways has led to their use by a spin-off biotech company, ParaTechs Corp., in the baculovirus protein expression vector system. A product related to this finding is now on the market. We continue to expand our understanding of the basic biology underlying this phenomenon in this project.